Domestic oven



R. L. PE RL DOMESTIC OVEN Dec. 24, 1968 5 Sheets-Sheet 1 Filed June 2.1967 INVENTOR RICHARD -L. PERL BY 0 I ,My, flmallycfm ATTORNEYS R. PERL3,417,742

DOMESTIC OVEN 5 Sheets -Sheetg Dec. 24, 1968 Filed June 5.. 1967INVENTOR ATTORNEYS RICHARD L. PERL ,iflaly,aamz@mw Dec. 24, 1968 PERL3,417,742

DOMESTIC OVEN Filed June 2. 1967 5 Sheets-Sheet 3 AIR TO BOTTOM BURNERINVENTOR RICHARD L. PERL BY 9%,MQM im ATTORNEYS United States Patent3,417,742 DOMESTIC OVEN Richard L. Perl, Mansfield, Ohio, assignor toThe Tappan Company, Mansfield, Ohio, a corporation of Ohio Filed June 2,1967, Ser. No. 643,104 7 Claims. (Cl. 12621) ABSTRACT OF THE DISCLOSUREA domestic gas-fired oven having a top burner in the cooking cavity anda bottom burner fully concealed beneath the bottom of the cavity, Theheated products of the bottom burner are caused to flow in a wrapperover the bottom and partially over the side walls to openings in thelatter where these products enter the cavity. Air under pressure issupplied to the burners by a fan and another fan withdraws flue productsfrom the top of the cavity, with the incoming air and the exhaustflowing through different sections of :a rotating regenerator wheel forheat transfer therebetween. The burners can be operated separately forbroiling and baking and together for high temperature self-cleaning ofthe oven.

DISCLOSURE This invention relates to oven structure for householdkitchen use and, more particularly, to an improved gasfired oven havingself-cleaning capacity.

It is a primary object of the invention to provide a single-cavity gascooking oven having bake, broil and self-cleaning conditions ofoperation, with the interior surfaces of the oven in such cleaning beingraised by a combination of radiant and convective heating effects to therelatively high temperature needed to effect decomposition ofaccumulated food soils thereon.

Another object is to provide such oven structure in which the cookingcavity is defined by a liner having a smooth, unobstructed andimperforate bottom, and at least two gas burners are used singly or incombination for the heating of the cavity.

It is also an object of the present invention to provide a domesticsingle-cavity oven having plural gas-fired heating devices to whichcombustion air is delivered under a pressure differential and under suchregulation that the air can thus be delivered selectively to one or moreof the devices.

A further object is to provide a multi-burner cooking oven in which roomair is supplied under pressure to the burners and flue products areexhausted from the oven in heat exchange relationship to the inflow ofthe room or ambient air.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends the invention,then, comprises the features hereiniafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawings setting forth in detail certain illustrativeembodiments of the invention, these being indicative, however, of but afew of the various ways in which the principle of the invention may beemployed.

In said annexed drawings:

FIG. 1 is a sectional view of domestic oven structure in accordance withthe present invention suitable for incorporation in a free-standingkitchen range shown in phantom outline;

FIG. 2 is a transverse cross-section of such oven structure as viewedfrom the plane of the line 22 in FIG. 1; and

FIG. 3 is an exploded perspective view of a combined air supply andexhaust assembly included in the oven structure.

Referring now to the drawings in detail, the dashed outline R will berecognized as depicting the form of a kitchen range cabinet andbackguard and is intended only to represent a conventional exemplaryenvironment for the oven structure which forms the present invention.

Such oven structure comprises a liner designated generally by referencenumeral 10 which is approximately cubical and open at the front foraccess, with the front opening of course to be closed by suitable ovendoor. The liner thus forms opposed side walls 11 and 12, rear wall 13,and bottom wall 14, with the latter flat or smooth, imperforate, andpreferably integral with the side walls as in a tub oven or one in whichthere is a continuous peripheral wrapper with rounded corners asillustrated. In the present construction, however, the top section ofsuch wrapper has an opening 15 extending substantially the full depth ofthe oven and between the two upper curved corner portions 16, 17, and arelatively shallow housing 18 open :at the bottom is applied to thewrapper to enclose such opening and form a plenum chamber 19. Suchhousing has a front wall 20 and side walls 21 and 22, respectively,which are inclined upwardly and inwardly from the corresponding marginsof the wrapper opening 15, and a rear vertical wall 23. A baffle plate24 extends from such chamber rear wall 23 horizontally forwardlysubstantially to the front wall 20* and is of such width as to extendfrom the longitudinal center of the chamber latenally more than half ofthe distance to the side wall at each side, with this baflle beingapproximately in the plane of the wrapper opening.

An elongated top burner 25 is disposed horizontally centrally beneaththe b aflie 24 in spaced relation, with its rear end supported on a gasspud 26 and its front end by suitable bracket 27, with the burnerpreferably being readily detached from such supports. The rear linerwall 13 has an opening 28 for a gas. line 29 connection of the spud toan available source of gaseous fuel under pressure and, for a purpose tobe described, this opening 28 is appreciably larger than the line 29 toprovide clearance about the latter. The gas burner 25 which has beenillustrated is of simple tubular form with two rows of ports 30 at therespective sides, and it will be appreciated that this device can be ofany specific form appropriate for use as a top or broiler burner,including the various screen and other incandescent types which :areessentially completely radiant heat generators.

The liner side wall 11 is provided with a plurality of apertures 31arranged in a horizontal row at an intermediate elevation, shown in theillustrated embodiment as just below the contiguous curved upper cornerportion 16, and the opposed side wall 12 is similarly provided withapertures 32. An outer wrapper 33 of channel form encloses the peripheryof the liner 10 from an exterior line on the side wall 11 just above theapertures 31 about the bottom 14 to a corresponding line just above theother side wall apertures 32. Such wrapper is closed at its ends 34 andhas a downwardly recessed removable bottom section 35 in which a secondor bottom gas burner 36 also of elongated ported form is housed inspaced relation centrally beneath the liner bottom 14. This. burnerhousing section 35 is preferably easily detached for convenient accessto the burner for servicing and the like, and the burner is supported atits front end by a block 37 and at the rear on a further gas spud 38having a fuel supply line 39. The wall which closes the rear of theburner housing section 35 has an opening 40 larger than the gas line 39through which the latter extends, so that this arrangement is similar tothat of the top burner in such respect.

An air supply duct 41 is arranged vertically behind the liner rear wall13 and has a forwardly directed upper end section 42 having a dischargeopening 43 and engaging the rear liner wall about the opening 28 in thelatter behind the end of the top burner. A further discharge opening isprovided in the lower end portion of the duct 41 in spaced register withthe rear wall opening behind the supply end of the bottom burner. Theduct has an intermediate inlet opening 45, through which air underpressure is admitted in a manner which will be described, and containstwo dampers 46 and 47 respectively above and below this inlet, withthese dampers operable by suitable linkages or the like, not shown, forcontrol of the air supply to the top and bottom burners as will also bemore fully explained hereinbelow.

The air supply duct 41 is in part enclosed by an exhaust manifold 48which extends generally from about the midpoint on such duct to a pointabove the top of the latter. This manifold has a forward top extension49 the end of which is against the rear wall 23 of the top plenumchamber 19, and the abutting sections are formed with registering slots50, 51 for outflow of flue products from the chamber. The manifold is,as shown most clearly in FIG. 3, wider than the air supply duct, and itsrear wall has two bottom outlets 52 respectively at the sides of theduct, so that flue products and the like entering the exhaust manifoldcan flow downwardly therethrough over the enclosed air supply duct 41 toand from such lower outlets 52.

A heat exchanger designated generally by reference numeral 53 isassociated with duct 41 and manifold 48, with this exchanger illustratedas comprising a housing 54 having one end against the duct and manifoldin the region of the inlet of the former and outlets 52 of the latter. Aregenerator wheel 55 having a multiplicity of axial passages issupported within the housing 54 on rollers 56, with its axis horizontal,and such wheel is rotated relatively slowly by drive means shown ascomprising an electric motor 57, a drive gear 58 on the motor shaft, anda toothed ring 59 affixed about the wheel or drum. Channels 60 and 61are horizontally disposed against the respective ends of the wheel 55and effectively divide the same into top and bottom halves. A flow plate62 is provided at the forward end of the housing 54 having an opening 63in register with the inlet 45 of the air supply duct 41 and with thecentral section of the top half of the wheel 55. Such plate is alsoprovided with a pair of lower openings 64 respectively in register withthe manifold outlets 52 and the bottom half of the wheel at the sectionsthereof outboard of the central section which corresponds to that inwhich the top half opening 63 is provided.

A second flow path 65 is applied to the rear end of the housing 54, andthis plate has an opening 66 in register with the central section of thebottom half of the wheel 55 and upper openings 67 registering with theoutboard sections at the top half, so that the openings of this secondplate are in relatively inverted arrangement as compared to those of thefirst plate 62.

A vertical exhaust duct 68 extends from the outer or rear flow plate 65of the heat exchanger, from the bottom half opening 66 in such plate, toremote blower means designated generally by reference numeral 69 and, inthe illustrated embodiment, adapted to be housed within the backguardassembly of the environmental kitchen range R. The exhaust duct 68 isenclosed within a large inlet air duct 70 having communication with thetop half openings 67 of the rear flow plate 65, with such inlet air ductalso extending to the blower means 69 and above the upper end of thevertical exhaust duct 68. Suchv blower means comprises an electric motor71 having right and left hand fans 72 and 73 on its drive shaft, withthe first fan 72 forcing room or ambient air into the upper end of theinlet duct 70 and the second fan 73 serving to draw flue products andgases from the upper end of the exhaust duct 68 and deliver the samethrough a discharge section 74 to the room. An air safety switch 75 isshown associated with the air supply fan 72, this switch including ahinged closure 76 for the outlet of this fan which is displaced when thefan is operating to permit the switch to open. Such safety can of coursebe incorporated in the control system for the oven to insure that thelatter cannot be operated unless the fan is supplying the pressurizedair to the burner or burners.

It will accordingly be evident that relatively cool ambient air flowsdownwardly through the inlet duct 70, and hence about the enclosedexhaust duct 68, to the upper half of the slowly rotating regeneratorwheel 55 through the flow plate openings 67. Such supply of air proceedsthrough the axial passages of the wheel and the forward flow plateopening 63 to the inlet 45 of the burner air supply duct 41 and,depending upon adjustment of the control dampers 46 and 47, this airunder pressure is delivered to either one or both of the burners 25 and36. The gases and vapors produced in the operation of the oven are drawnabout the edges of the top oven baffle 24 into the plenum chamber 19 andproceed from this chamber downwardly through the exhaust manifold 48 andthrough the outlets 52 thereof and the forward flow plate openings 64 tothe bottom half of the rotating drum or wheel 55. These flue productsproceed through the bottom half of the wheel, giving up heat thereto,then continue through the rear flow plate opening 66 to the verticalexhaust duct 68 and the suction fan 73.

This regenerator wheel type of heat exchanger is known and may comprise,for example, spirally wrapped corrugated asbestos sheet impregnated withsodium silicate. It will also be apparent that the incoming relativelycool air and the flue products exhaust are in heat exchange relationshipin both the manifolding between the regenerator wheel and the oven andin the vertical ducting which extends over substantial distance from theother side of the regenerator Wheel. This heat exchange serves to lowerthe temperature of the ultimate exhaust to the room to such tolerablelevel that even the high temperature cleaning cycle can be carried outwithout the need for venting to the outside of the house. The use ofpressurized air to the burners also permits conservation of thesecondary air for combustion, whereby the heat output is also relativelydiminished on this account. The housing for the concealed bottom burner36 can be provided if necessary with a plurality of apertures 77 toprovide added secondary air in this area.

The controls for the oven have not been shown and will of course beconventional. As is also conventional, the top burner 26 is utilized forbroiling and like operations in the normal use of the oven and, for thiscondition, upper damper 46 in the air supply duct 41 will be fullyopened and lower damper 47 fully closed, whereby all of the room airsupply is delivered to the top burner. As earlier noted, this burnercould be of full radiant type, and it is also possible that the baffle24 closely above the same could be made of or coated with a readilyincandescing material or carry screening to be heated by the flame toadd the baflie area as a radiating source.

For baking and roasting in the oven, only the concealed bottom burner 36will be operative, with the air supply damper 47 fully open and damper46 fully closed. The heated products from the bottom burner of courseflow upwardly through wrapper 33 over the exterior surfaces of the ovenbottom 14 and enclosed portions of the side walls 11, 12 to and throughthe apertures 31, 32 respectively at the sides and from the latter tothe top plenum chamber 19 for exhaust therefrom in the manner previouslydescribed.

It has been determined that the usual food soils which accumulate on theinterior surfaces of a cooking oven can be incinerated at a temperatureof about 750 F., and

the oven herein disclosed is intended also for operation at and abovethis temperature. Such heat-cleaning cycle is carried out bysimultaneous firing of both burners for combined radiant and convectiveheating effect, with the radiant effect provided by the top burnerlargely directed beneficially to the smooth bottom of the oven whichusually receives most of the drippings and the like which cause thesoiling. In such high temperature cleaning cycle, both of the air supplydampers 46 and 47 will preferably be half open for division of thepressurized air substantially equally to the two burners. The oven willbe of course suitably insulated and preferably constructed to withstandcavity temperatures on the order of 1000 F.

The circulation of the products of the fully concealed bottom burnerthrough the upper portion of the cooking cavity provides the disclosedsingle point of collection, in the top plenum chamber, for theexhausting of the cavity, which facilitates the handling of the exhaustand also the preferred heat exchange relationship of the incoming airtherewith. The regenerator wheel used in this connec tion can bereplaced by other exchangers of known design and, in some cases, thepreheating of the incoming air may not be utilized, for example, where ahigher level of exhaust heat might be tolerated. With adequate sealingof the cavity, a single fan at either the supply or exhaust might alsoserve to provide the desired circulation, but the two fans used asdisclosed conveniently provide by adjustment or selection thereof eithera negative or positive pressure to be maintained within the cavity asdesired. It has, for example, been found that a slight positive pressurecan be beneficial in the heat cleaning of the oven door surface, andthis condition can readily be realized by using fans of suitablediffering capacity. A more sophisticated system might provide variationof the pressure over a range of negative and positive values within atime-controlled operating cycle.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. A domestic oven comprising a liner forming a cooking cavity havingtop, bottom, side and rear walls, the bottom wall being substantiallysmooth and imperforate, broiler burner means mounted in the upperportion of said cavity, with the top wall thereabove having an openingfor exhaust of the cavity, bake burner means disposed exteriorly of thecavity, means for delivering combustion air under pressure selectivelyto either the broiler or bake burner or both, means for circulating theheated products from the bake burner in operation over exterior surfacesof the bottom and side walls, the latter being provided with openingsfor inflow of such heated products to the cavity and exhaust therefromthrough the top wall opening, and means for directing the flue productsfrom such top wall opening to a remote discharge.

2. A domestic oven comprising a liner forming a cooking cavity havingtop, bottom, side and rear Walls, the bottom wall being substantiallysmooth and imperforate, broiler burner means mounted in the upperportion of said cavity, with the top wall thereabove having an openingfor exhaust of the cavity, bake burner means disposed exteriorly of thecavity, means for circulating the heated products from the bake burnerin operation over exterior surfaces of the bottom and side Walls, thelatter being provided with openings for inflow of such heated productsto the cavity and exhaust therefrom through the top wall opening, meansfor directing the flue products from such top wall opening to a remotedischarge, and means for delivering ambient air to at least one burnerin heat exchange relationship to the flue products withdrawn from thecavity.

3. A domestic oven comprising a liner forming a cooking cavity havingtop, bottom, side and rear walls, the bottom wall being substantiallysmooth and imperforate, broiler burner means mounted in the upperportion of said cavity, with the top wall thereabove having an openingfor exhaust of the cavity, bake burner means disposed exteriorly of thecavity, means for circulating the heated products from the bake burnerin operation over exterior surfaces of the bottom and side walls, thelatter being provided with openings for inflow of such heated productsto the cavity and exhaust therefrom through the top wall opening, meansfor directing the flue products from such top wall opening to a remotedischarge, and means for delivering ambient air under pressureselectively to one or both of the broiler and bake burners in heatexchange relationship to the flue products exhausted from the cavity.

4. A domestic oven comprising a liner forming a cooking cavity havingtop, bottom, side and rear walls, the bottom Wall being substantiallysmooth and imperforate, broiler burner means mounted in the upperportion of said cavity, with the top wall thereabove having an openingfor exhaust of the cavity, bake burner means disposed exteriorly of thecavity, blower means for causing ambient air to flow to the burnersunder a pressure differential, flow-regulating means for directing suchambient air fiow substantially fully to either the broiler or bakeburner, respectively for broiling and baking operations, or dividing theflow between the two burners for joint operation thereof at a relativelyhigh-temperature self-cleaning cycle, means for circulating the heatedproducts from the bake burner in operation over exterior surfaces of thebottom and side walls, the latter being provided with openings forinflow of such heated products to the cavity and exhaust therefromthrough the top Wall opening, and means for directing the flue productsfrom such top Wall opening to a remote discharge.

5. A domestic oven comprising a liner forming acooking cavity havingtop, bottom, side and rear walls, the bottom wall being substantiallysmooth and imperforate, broiler burner means mounted in the upperportion of said cavity, with the top wall thereabove having an openingfor exhaust of the cavity, bake burner means disposed exterriorly of thecavity, first fan means for delivering ambient air under pressure to atleast one burner, means for circulating the heated products from thebake burner in operation over exterior surfaces of the bottom and sidewalls, the latter being provided with openings for inflow of such heatedproducts to the cavity and exhaust therefrom through the top wallopening, and second fan means for withdrawing the flue products from thecavity through the top exhaust opening thereof to a remote discharge.

6. An oven as set forth in claim 5, including an electric motor commonlydriving the first and second fan means in counter-rotating relation.

7. An oven as set forth in claim 6, including means for bringing theambient air delivered by the first fan means into heat exchangerelationship to theflue products exhausted by the second fan means.

References Cited UNITED STATES PATENTS 1,224,497 5/1917 ODowd l2621 X1,342,991 6/1920 Erskine 126-39 2,350,293 5/1940 Stanchfield 12621 X3,169,871 2/1965 Macchi et al. 12639X 3,255,746 6/1966 Jenn et a1. 12621FREDERICK L. MATTESON, IR., Primary Examiner.

E. G. FAVORS, Assistant Examiner.

